Industrial systems are publicly the target of cyberattacks since Stuxnet. Nowadays they are increasingly communicating over insecure media such as In-ternet. Due to their interaction with the real world, it is crucial to ensure their security. In this paper, we propose a domain specific stateful filtering that keeps track of the value of predetermined variables. Such filter allows to express rules depending on the context of the system. Moreover, it must guarantee bounded memory and execution time to be resilient against malicious adversaries. Our approach is illustrated on an example.